Kämpfer, Ore, Twintail ni Narimasu. Recommendations
Both are gender bender anime that revolve around a guy transforming into a magical girl. Both will make you question you sexuality
In both shows, the character transforms into a girl in order to fight. Kampfer isn't as action oriented, mostly comedy and Ore, Twintail ni Narimasu is both action and comedy oriented.
Both are, what have you, "magical girl" anime, in a sense.
The only major difference would be that Natsuru doesn't like transforming into a girl while Soji...well, he does because he likes twintails.
Transforming from boy into a girl is what connects these anime the most. Senou Natsuru from Kämpfer have to do it against his will, but for Mitsuka Souji from Ore, Twintails ni Narimasu. it's just a side-effect of using battle-suit. Both shows have elements of mahō-shōjo, romance, comedy and ecchi, and Gonna be the Twin-Tails!! has also some elements of mecha.
If you liked one of those, it's very likely you would like the other.
* In both shows, tha main male character transforms into a girl.
* The main character have a childhood friend and the Student council president joins to their team.
* Both have some fanservice. (Twintail less than Kampfer)
* Similar genres
Both are amazing comedies with a gender-bent main character, who has to learn to deal with living as a girl. Kampfer is more full-on with this, as the main takes a while to learn to control the transformations, while TailRed mostly controls his transformations...
They're both about boy turning into a girl and fighting villains. Twin tail the boy is more self sustain, unlike Kampfer.